As technology advances, product designs in general, and designs for mobile products in particular, concentrate on aesthetics and durability. Durable metal housings for products typically receive surface treatments to alter physical appearance and characteristics which increase the aesthetic quality perceived by a user. For example, anodized aluminum in particular is a conventional manner in which to provide a cosmetic surface with reasonable durability having unique aesthetic characteristics. Different colors may be applied through dyes for cosmetic appeal and sealing techniques may further be applied for durability. Glass cover substrates, plastic substrates, and other substrates may also be used. Typically, paint and/or hard sealants may be applied to enhance their durability and appearance. However, graphical appliques and other enhancements beneath sealing layers may cause disturbances in the otherwise smooth sealant surface. For example, traditional inks and pigments require significant thickness to achieve opacity (e.g., about 40 μm in white pigments). Application of a sealing layer about these traditional inks would cause a step to form, thereby detracting from cosmetic appeal. Furthermore, even if using traditional inks and pigments to color a large area absent visible transitions, the increased thickness may cause further problems due to changes in overall substrate thickness.
Therefore, what is desired are methods to alter color and perceived color of surfaces and/or portions thereof without the drawbacks of traditionally bulky pigment layers.